Fluid Changes

[mxzeatr]

Hi all,

I have a 99 Z71 Ext Cab....

 

I am looking at changing the fluids in the Front Diff, Transfer Case, Tranny, and Rear Diff. I was wondering what types of fluids I need. I just got the truck not too long ago and I am not sure when they were done, so I'd rather do it my self just to know....Also capacities would be very helpful! Thanks guys...This site rocks!

 

Eric

[mxzeatr]

No one else has changed thier fluids? Please help...I just want to know what types of fluids basically...I don't need brands or quantities etc....

[jason2006]

you need differential fluid, transfer case fluid, and power steering fluid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No one else has changed thier fluids? Please help...I just want to know what types of fluids basically...I don't need brands or quantities etc....

 

<{POST_SNAPBACK}>

 

 

[01z71]

For my'01 I use the Autotrac II (Blue) Fluid for the Transfer Case. Don't forget to get the fill and drain bolts about $4.00. I replace those when I change the T-Case Fluid.

 

Trans. Fluid is Dexron III -- I drop the pan and change the fliter as well as cleaning the magnet. I had to use a Craftsman Stripped Bolt Type Extractor to get the 15MM drain bolt out. I tried my sockets but it started stripping the bolt.

 

Power Steering Fluid I use the turkey baster method to suck the fluid out. Over the course of a couple of days I figure I get most of the old fluid out by doing this. Most people do not change this. I do it once a year and it always comes out clear. I use the GM Fluid.

 

Front & Rear Axle I use 75W90 Amsoil Synthetic Fluid. A lot of guys here use Mobil 1 since it is more readily available in Auto Stores, Wal-Mart, etc...

 

 

You may want to replace the fuel filter as well as long as you are at it. Good Luck!

[C & A s Dad]

I really cannot help you with the diff capacities but for sure use syn and the correct weight as called for in your Owner's Manual if you have it. I believe it is 75W 90.

 

For the trans, if you drop the pan and replace the filter you will need approx 5 qts.

 

If your drain plug has not already been rounded off, you can likely get it out using a 6 pt Impact Style (black) socket. Make sure you have it on the plug all the way and you should have no problem. I have seen some guys heat it slightly with a propane torch. This will melt the threadlocker and make it come out much easier.

[mxzeatr]

Thanks guys! Should I put threadlocker back on the plug? Or is it not necessary?

 

Also where to I get the AutoTrac II fluid? Is that something I get at the dealer or??? Thanks!

[c4cruiser]

AutoTracII fluid is a GM fluid p/n 12378396. You can get it at a Chevy or GMC dealer.

 

The front diff uses a 80W-90 gear oil and the rear uses 75W-90 synthetic gear oil. For whatever reason, the owner's manual does not specify a synthetic fluid in the front differential, just the rear diff.

 

You didn't mention the miles on your truck, but if it's over 60K, I would go with a full flush of the tranny along with a new filter. Changing the fluid in the pan doesn't change out the remaining fluid in the tranny, the cooling lines or tranny cooler, and torque converter. Go to a reputable shop that uses a machine to flush the old fluid out and have it done along with a filter.

 

A Brake fluid flush would be a good thing to do at the same time. Look at the fluid in the master cylinder reservoir; if it's really dark, it should be changed.

 

If the cooling system hasn't been flushed, get that done too. DexCool is supposedly good for 5 years and the truck is abut 7 years old.

[mxzeatr]

Thanks! Not sure on the tranny flush right now, that will have to wait a bit for money reasons....The brake fluid looks good, not sure if it was flushed or just had new added when the brakes were done.

 

Should I put synthetic in both diffs? Is it going to hurt anything? Or should I just do the 80w-90 in the front and 75w-90 in the rear? A post above stated 75w-90 synthetic in both....Sorry I'm new to this so thank you very much for the info!

[tnord]

toss 75/90 syn in both front and rear, it'll work just fine.

[Black02Silverado]

Sounds like everyone has it covered for you. 75w-90 will work in both differentials just fine.

 

You can follow this reference to change out the transmission fluid. It isn't hard to do at all. Having an extra person helps.

 

Auto Trac II is the only fluid for the auto trac transfer case and you can only get it at the dealer. It isn't expensive and you will need 2 qts to do the Tcase.

[mxzeatr]

Thanks a lot!